/**
 * Copyright (c) 2011-2014, hubin (jobob@qq.com).
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.baomidou.kisso.common.captcha.filter.library;

import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Random;

import com.baomidou.kisso.common.captcha.color.ColorFactory;
import com.baomidou.kisso.common.captcha.color.SingleColorFactory;

/**
 * 图片曲线
 */
public class CurvesImageOp extends AbstractImageOp {

	private float strokeMin;
	private float strokeMax;
	private ColorFactory colorFactory = new SingleColorFactory();

	public float getStrokeMin() {
		return strokeMin;
	}

	public void setStrokeMin(float strokeMin) {
		this.strokeMin = strokeMin;
	}

	public float getStrokeMax() {
		return strokeMax;
	}


	public void setStrokeMax(float strokeMax) {
		this.strokeMax = strokeMax;
	}
	public ColorFactory getColorFactory() {
		return colorFactory;
	}

	public void setColorFactory(ColorFactory colorFactory) {
		this.colorFactory = colorFactory;
	}

	private double hermiteSpline(double x1, double a1, double x2, double a2, double t) {
		double t2=t*t;
	    double t3=t2*t;
	    double b=-a2-2.0*a1-3.0*x1+3.0*x2;
	    double a=a2+a1+2.0*x1-2.0*x2;
	    return a*t3+b*t2+a1*t+x1;	    
	}
	
	private double catmullRomSpline(double x0, double x1, double x2, double x3, double t) {
		double a1 = (x2 - x0) / 2;
		double a2 = (x3 - x1) / 2;
		return hermiteSpline(x1, a1, x2, a2, t);
	}

	@Override
	public BufferedImage filter(BufferedImage src, BufferedImage dest) {
		if (dest == null) {
			dest = createCompatibleDestImage(src, null);
		}
		double width = dest.getWidth();
		double height = dest.getHeight();
		Graphics2D g2 = (Graphics2D) src.getGraphics();
		g2.setRenderingHints(new RenderingHints(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON));
		Random r = new Random();
		int cp = 4 + r.nextInt(3);
		int[] xPoints = new int[cp];
		int[] yPoints = new int[cp];
		width -= 10;
		for (int i = 0; i < cp; i++) {
			xPoints[i] = (int) ((int) 5 + (i * width) / (cp - 1));
			yPoints[i] = (int) (height * (r.nextDouble() * 0.5 + 0.2));
		}
		int subsections = 6;
		int[] xPointsSpline = new int[(cp - 1)*subsections];
		int[] yPointsSpline = new int[(cp - 1)*subsections];
		for (int i = 0; i < cp - 1; i++) {
			double x0 = i > 0 ? xPoints[i - 1] : 2 * xPoints[i] - xPoints[i + 1];
			double x1 = xPoints[i];
			double x2 = xPoints[i + 1];
			double x3 = (i + 2 < cp) ? xPoints[i + 2] : 2 * xPoints[i + 1] - xPoints[i];
			double y0 = i > 0 ? yPoints[i - 1] : 2 * yPoints[i] - yPoints[i + 1];
			double y1 = yPoints[i];
			double y2 = yPoints[i + 1];
			double y3 = (i + 2 < cp) ? yPoints[i + 2] : 2 * yPoints[i + 1] - yPoints[i];
			for (int j = 0; j < subsections; j++) {
				xPointsSpline[i * subsections + j] = (int) catmullRomSpline(x0, x1, x2, x3, 1.0 / subsections * j); 
				yPointsSpline[i * subsections + j] = (int) catmullRomSpline(y0, y1, y2, y3, 1.0 / subsections * j); 
			}
		}
		for (int i = 0; i < xPointsSpline.length - 1; i++) {
			g2.setColor(colorFactory.getColor(i));
			g2.setStroke(new BasicStroke(2 + 2 * r.nextFloat()));
			g2.drawLine(xPointsSpline[i], yPointsSpline[i], xPointsSpline[i + 1], yPointsSpline[i + 1]);
		}
		return src;
	}
}
